Attacks could include explosives planted on trains and tunnels or sabotage to tracks and electrical cabling, said Europe’s most widely read daily newspaper.

Bild said the information came from the National Security Agency (NSA) in the United States, which had listened in to a conference call involving high-ranking al-Qaeda operatives in which attacks on Europe’s rail network was a “central topic” of this call, the Bild said.

Authorities in Germany have responded to the threat by deploying plain-clothed police officers at key stations and on main routes.

Terror alerts have been at an all-time high this month due to an earlier call between al-Qaeda leader al-Zawahiri and other operatives.

This prompted the U.S. and several allies to temporarily shut embassies across the Muslim world, warning of al-Qaeda plans to launch an attack in the Middle East or North Africa.(Courtesy:al arabia)